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1.
Liver Int ; 40(1): 83-91, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31498528

RESUMO

BACKGROUND: Tenofovir disoproxil fumarate (TDF) imposes a high genetic barrier to drug resistance and potently inhibits replication of multidrug-resistant hepatitis B virus. Few clinical cases with confirmed TDF-resistance have been reported to date. METHODS AND RESULTS: Here, we report viral rebound in a patient with chronic hepatitis B who underwent TDF monotherapy and harboured a quadruple mutant consisting of classic entecavir (ETV)-resistance mutations (rtL180M/T184L/M204V) together with an rtA200V mutation in the reverse transcriptase gene. Sequencing analysis revealed that this quadruple mutant emerged as a major viral population. In vitro phenotyping demonstrated that the rtL180M/T184L/A200V/M204V mutant had moderate resistance to TDF treatment, with a 4.52-fold higher half maximal effective concentration than that of wild-type virus. Importantly, this patient with TDF resistance achieved virological suppression after TDF/ETV combination rescue therapy. CONCLUSION: An rtL180M/T184L/A200V/M204V mutant with moderate resistance to TDF monotherapy was selected during sequential nucleoside analogue (NA) treatment in a stepwise manner. ETV/TDF combination therapy effectively suppressed replication of this TDF-resistant mutant. Our studies provide novel insights into the treatment of NA-naïve patients as well as patients with TDF resistance.

2.
Emerg Microbes Infect ; 8(1): 1511-1523, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31631785

RESUMO

Interferons (IFNs) control viral infections by inducing expression of IFN-stimulated genes (ISGs) that restrict distinct steps of viral replication. We report herein that gamma-interferon-inducible lysosomal thiol reductase (GILT), a lysosome-associated ISG, restricts the infectious entry of selected enveloped RNA viruses. Specifically, we demonstrated that GILT was constitutively expressed in lung epithelial cells and fibroblasts and its expression could be further induced by type II interferon. While overexpression of GILT inhibited the entry mediated by envelope glycoproteins of SARS coronavirus (SARS-CoV), Ebola virus (EBOV) and Lassa fever virus (LASV), depletion of GILT enhanced the entry mediated by these viral envelope glycoproteins. Furthermore, mutations that impaired the thiol reductase activity or disrupted the N-linked glycosylation, a posttranslational modification essential for its lysosomal localization, largely compromised GILT restriction of viral entry. We also found that the induction of GILT expression reduced the level and activity of cathepsin L, which is required for the entry of these RNA viruses in lysosomes. Our data indicate that GILT is a novel antiviral ISG that specifically inhibits the entry of selected enveloped RNA viruses in lysosomes via disruption of cathepsin L metabolism and function and may play a role in immune control and pathogenesis of these viruses.


Assuntos
Ebolavirus/fisiologia , Doença pelo Vírus Ebola/imunologia , Febre Lassa/imunologia , Vírus Lassa/fisiologia , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/imunologia , Vírus da SARS/fisiologia , Síndrome Respiratória Aguda Grave/imunologia , Proteínas do Envelope Viral/metabolismo , Internalização do Vírus , Catepsina L/genética , Catepsina L/imunologia , Linhagem Celular , Ebolavirus/genética , Doença pelo Vírus Ebola/genética , Doença pelo Vírus Ebola/virologia , Humanos , Febre Lassa/genética , Febre Lassa/virologia , Vírus Lassa/genética , Lisossomos/genética , Lisossomos/imunologia , Lisossomos/virologia , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/genética , Vírus da SARS/genética , Síndrome Respiratória Aguda Grave/genética , Síndrome Respiratória Aguda Grave/virologia , Proteínas do Envelope Viral/genética , Replicação Viral
3.
Materials (Basel) ; 12(19)2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31546672

RESUMO

The micro-groove structure on the planar surface has been widely used in the tribology field for improving the lubrication performance, thereby reducing the friction coefficient and wear. However, in the conventional cutting (CC) process, the high-quality, high-precision machining of the micro-groove on titanium alloy has always been a challenge, because considerable problems including poor surface integrity and a high level of the material swelling and springback remain unresolved. In this study, the ultrasonic elliptical vibration assisted cutting (UEVC) technology was employed, which aimed to minimize the level of the material swelling and springback and improve the machining quality. A series of comparative investigations on the surface defect, surface roughness, and material swelling and springback under the CC and UEVC processes were performed. The experimental results certified that the material swelling and springback significantly reduced and the surface integrity obviously improved in the UEVC process in comparison to that in the CC process. Furthermore, for all the predetermined depths of the cut, when the TSR (the ratio of the nominal cutting speed to the peak horizontal vibration speed) was equal to one of twenty four or one of forty eight, the accuracy of the machined micro-groove depth, width and the profile radius reached satisfactorily to 98%, and the roughness values were approximately 0.1 µm. The experimental results demonstrate that the UEVC technology is a feasible method for the high-quality and high-precision processing of the micro-groove on Ti-6Al-4V alloy.

4.
Micromachines (Basel) ; 9(10)2018 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-30424468

RESUMO

In this paper, a novel single-driven ultrasonic elliptical vibration cutting (SDUEVC) device with a succinct structure and a simple assembly is proposed and investigated. A tailored horn with a tilted-slot structure was employed in the designed SDUEVC device. Also, the elliptical trajectory formation mechanism of the designed SDUEVC device was described by using the theory of mechanical vibration. Furthermore, the finite element method (FEM) was used to optimize the tilted-slot structure parameters and there are four parameters selected as the optimization factors. The results indicated that the proposed SDUEVC device can generate larger vertical amplitude than previous SDUEVC devices, which provides an important and positive effect for the cutting performance of the proposed SDUEVC device. According to the optimized results, a prototype SDUEVC device was fabricated and its vibration characteristic was tested. When the excitation signal voltage was 500 Vp-p, the test results indicated that the amplitudes in the axial and vertical directions were 8.7 µm and 6.8 µm, respectively. Furthermore, an elliptical trajectory was generated at the cutting tool tip. Finally, the proposed SDUEVC device was used to fabricate microdimple patterns as the initial application to confirm the feasibility of the proposed SDUEVC device.

5.
PLoS Negl Trop Dis ; 12(9): e0006738, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30188905

RESUMO

The yellow fever virus (YFV) recently reemerged in the large outbreaks in Africa and Brazil, and the first imported patients into Asia have recalled the concerns of YFV evolution. Here we show phylogenomics of YFV with serial clinical samples of the 2016 YFV infections. Phylogenetics exhibited that the 2016 strains were close to Angola 1971 strains and only three amino acid changes presented new to other lineages. Deep sequencing of viral genomes discovered 101 intrahost single nucleotide variations (iSNVs) and 234 single nucleotide polymorphisms (SNPs). Analysis of iSNV distribution and mutated allele frequency revealed that the coding regions were under purifying selection. Comparison of the evolutionary rates estimated by iSNV and SNP showed that the intrahost rate was ~2.25 times higher than the epidemic rate, and both rates were higher than the long-term YFV substitution rate, as expected. In addition, the result also hinted that short viremia duration of YFV might further hinder the evolution of YFV.


Assuntos
Evolução Molecular , Filogenia , Polimorfismo de Nucleotídeo Único , Vírus da Febre Amarela/classificação , Vírus da Febre Amarela/genética , Genoma Viral , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Taxa de Mutação , Febre Amarela/virologia , Vírus da Febre Amarela/isolamento & purificação
6.
Front Microbiol ; 9: 3228, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30687247

RESUMO

Interferon-induced transmembrane proteins (IFITMs) are a family of small proteins that localize in the plasma and endolysosomal membranes. IFITMs not only inhibit viral entry into host cells by interrupting the membrane fusion between viral envelope and cellular membranes, but also reduce the production of infectious virions or infectivity of progeny virions. Not surprisingly, some viruses can evade the restriction of IFITMs and even hijack the antiviral proteins to facilitate their infectious entry into host cells or promote the assembly of virions, presumably by modulating membrane fusion. Similar to many other host defense genes that evolve under the selective pressure of microorganism infection, IFITM genes evolved in an accelerated speed in vertebrates and many single-nucleotide polymorphisms (SNPs) have been identified in the human population, some of which have been associated with severity and prognosis of viral infection (e.g., influenza A virus). Here, we review the function and potential impact of genetic variation for IFITM restriction of viral infections. Continuing research efforts are required to decipher the molecular mechanism underlying the complicated interaction among IFITMs and viruses in an effort to determine their pathobiological roles in the context of viral infections in vivo.

7.
J Virol ; 92(6)2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29263263

RESUMO

Interferon-induced transmembrane proteins (IFITMs) are restriction factors that inhibit the infectious entry of many enveloped RNA viruses. However, we demonstrated previously that human IFITM2 and IFITM3 are essential host factors facilitating the entry of human coronavirus (HCoV) OC43. In a continuing effort to decipher the molecular mechanism underlying IFITM differential modulation of HCoV entry, we investigated the roles of structural motifs important for IFITM protein posttranslational modifications, intracellular trafficking, and oligomerization in modulating the entry of five HCoVs. We found that three distinct mutations in IFITM1 or IFITM3 converted the host restriction factors to enhance entry driven by the spike proteins of severe acute respiratory syndrome coronavirus (SARS-CoV) and/or Middle East respiratory syndrome coronavirus (MERS-CoV). First, replacement of IFITM3 tyrosine 20 with either alanine or aspartic acid to mimic unphosphorylated or phosphorylated IFITM3 reduced its activity to inhibit the entry of HCoV-NL63 and -229E but enhanced the entry of SARS-CoV and MERS-CoV. Second, replacement of IFITM3 tyrosine 99 with either alanine or aspartic acid reduced its activity to inhibit the entry of HCoV-NL63 and SARS-CoV but promoted the entry of MERS-CoV. Third, deletion of the carboxyl-terminal 12 amino acid residues from IFITM1 enhanced the entry of MERS-CoV and HCoV-OC43. These findings suggest that these residues and structural motifs of IFITM proteins are key determinants for modulating the entry of HCoVs, most likely through interaction with viral and/or host cellular components at the site of viral entry to modulate the fusion of viral envelope and cellular membranes.IMPORTANCE The differential effects of IFITM proteins on the entry of HCoVs that utilize divergent entry pathways and membrane fusion mechanisms even when using the same receptor make the HCoVs a valuable system for comparative investigation of the molecular mechanisms underlying IFITM restriction or promotion of virus entry into host cells. Identification of three distinct mutations that converted IFITM1 or IFITM3 from inhibitors to enhancers of MERS-CoV or SARS-CoV spike protein-mediated entry revealed key structural motifs or residues determining the biological activities of IFITM proteins. These findings have thus paved the way for further identification of viral and host factors that interact with those structural motifs of IFITM proteins to differentially modulate the infectious entry of HCoVs.


Assuntos
Antígenos de Diferenciação/metabolismo , Coronavirus/metabolismo , Proteínas de Membrana/metabolismo , Mutação de Sentido Incorreto , Multimerização Proteica , Proteínas de Ligação a RNA/metabolismo , Internalização do Vírus , Motivos de Aminoácidos , Substituição de Aminoácidos , Antígenos de Diferenciação/genética , Linhagem Celular Tumoral , Coronavirus/genética , Humanos , Proteínas de Membrana/genética , Proteínas de Ligação a RNA/genética , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo
8.
Rev Sci Instrum ; 88(11): 115109, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29195400

RESUMO

This paper presents a novel atomic force microscopy (AFM)-based 5-axis nanoscale machine tool developed to fabricate nanostructures on different annuli of the micro ball. Different nanostructures can be obtained by combining the scratching trajectory of the AFM tip with the movement of the high precision air-bearing spindle. The center of the micro ball is aligned to be coincided with the gyration center of the high precision to guarantee the machining process during the rotating of the air-bearing spindle. Processing on different annuli of the micro ball is achieved by controlling the distance between the center of the micro ball and the rotation center of the AFM head. Nanostructures including square cavities, circular cavities, triangular cavities, and an annular nanochannel are machined successfully on the three different circumferences of a micro ball with a diameter of 1500 µm. Moreover, the influences of the error motions of the high precision air-bearing spindle and the eccentric between the micro ball and the gyration center of the high precision air-bearing spindle on the processing position error on the micro ball are also investigated. This proposed machining method has the potential to prepare the inertial confinement fusion target with the expected dimension defects, which would advance the application of the AFM tip-based nanomachining approach.

9.
Artigo em Inglês | MEDLINE | ID: mdl-28717041

RESUMO

Induction of interferon and proinflammatory cytokines is a hallmark of the infection of many different viruses. However, hepatitis B virus (HBV) does not elicit a detectable cytokine response in infected hepatocytes. In order to investigate the molecular mechanism underlying the innate immune evasion, a functional cyclic GMP-AMP (cGAMP) synthase (cGAS)-stimulator of interferon genes (STING) pathway was reconstituted in a human hepatoma cell line supporting tetracycline-inducible HBV replication. It was demonstrated that induction of HBV replication neither activated nor inhibited this cytosolic DNA sensing pathway. However, human hepatoma cells, as well as immortalized mouse hepatocytes, express low levels of STING, which upon activation by cGAMP, the natural ligand of STING, led to induction of a proinflammatory cytokine response. Treatment of immortalized mouse hepatocytes supporting HBV replication with either cGAMP or a small molecule pharmacologic STING agonist significantly reduced viral DNA in a STING- and Janus kinase 1-dependent manner. Moreover, cGAMP treatment was able to induce inflammatory cytokine gene expression and inhibit the transcription of covalently closed circular DNA in HBV-infected human hepatoma cells expressing sodium taurocholate cotransporting polypeptide, an essential receptor for HBV infection of hepatocytes. The studies reported here and previously (F. Guo et al., Antimicrob Agents Chemother 59:1273-1281, 2015, https://doi.org/10.1128/AAC.04321-14) thus support the notion that pharmacological activation of STING in macrophages and hepatocytes induces host innate responses that can efficiently control HBV replication. Hence, despite not playing a significant role in host innate immune response to HBV infection of hepatocytes, STING is potentially a valuable target for immunotherapy of chronic hepatitis B.


Assuntos
Vírus da Hepatite B/crescimento & desenvolvimento , Hepatócitos/imunologia , Interferons/biossíntese , Macrófagos/imunologia , Proteínas de Membrana/metabolismo , Replicação Viral/genética , Animais , Antivirais/farmacologia , Linhagem Celular Tumoral , Células Hep G2 , Vírus da Hepatite B/imunologia , Hepatite B Crônica/tratamento farmacológico , Hepatite B Crônica/virologia , Hepatócitos/metabolismo , Hepatócitos/virologia , Humanos , Interferons/imunologia , Macrófagos/metabolismo , Macrófagos/virologia , Proteínas de Membrana/agonistas , Camundongos , Nucleotidiltransferases/metabolismo , Transportadores de Ânions Orgânicos Dependentes de Sódio/metabolismo , Simportadores/metabolismo
10.
Scanning ; 38(6): 612-618, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26890820

RESUMO

This paper presents a reliable nanolithography technique, namely dynamic plowing lithography (DPL) based on a commercial atomic force microscope (AFM). The poly(methyl methacrylate) (PMMA) solution spinning on a silicon substrate is utilized to be scratched directly with an oscillating tip at its resonance frequency. The films with different thickness are obtained by adjusting the concentration of solution and post baked time. A new silicon tip is employed to conduct DPL on PMMA film surface. The geometry of nano-line structure scratched on the film with high adhesion force is shown with a transition process, including total protuberance, protuberance with groove and groove with pile-up. The scratching direction has less influence on the scratched depth of groove, while the shape of pile-up is varied with directions. The depth of groove on thin films is increasing with the drive amplitude until the value of the depth reaches to the threshold value. Moreover, owing to smaller elastic modulus, the film with relatively large thickness could be modified by the tip more easily using this DPL method. SCANNING 38:612-618, 2016. © 2016 Wiley Periodicals, Inc.

11.
Ultramicroscopy ; 160: 155-162, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26517548

RESUMO

The measurement resolution of an atomic force microscope (AFM) is largely dependent on the radius of the tip. Meanwhile, when using AFM to study nanoscale surface properties, the value of the tip radius is needed in calculations. As such, estimation of the tip radius is important for analyzing results taken using an AFM. In this study, a geometrical model created by scanning a step structure with an AFM tip was developed. The tip was assumed to have a hemispherical cone shape. Profiles simulated by tips with different scanning radii were calculated by fast Fourier transform (FFT). By analyzing the influence of tip radius variation on the spectra of simulated profiles, it was found that low-frequency harmonics were more susceptible, and that the relationship between the tip radius and the low-frequency harmonic amplitude of the step structure varied monotonically. Based on this regularity, we developed a new method to characterize the radius of the hemispherical tip. The tip radii estimated with this approach were comparable to the results obtained using scanning electron microscope imaging and blind reconstruction methods.

12.
ACS Appl Mater Interfaces ; 7(29): 16046-53, 2015 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-26173649

RESUMO

In this work, we experimentally demonstrated the new functions of trivalent rare earth complex in improving the electroluminescent (EL) performances of iridium complex by codoping trace Eu(TTA)3phen (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline) into a light-emitting layer based on PQ2Ir(dpm) (iridium(III)bis(2-phenylquinoly-N,C(2'))dipivaloylmethane). Compared with a reference device, the codoped devices displayed higher efficiencies, slower efficiency roll-off, higher brightness, and even better color purity. Experimental results demonstrated that Eu(TTA)3phen molecules function as electron trappers due to its low-lying energy levels, which are helpful in balancing holes and electrons and in broadening recombination zone. In addition, the matched triplet energy of Eu(TTA)3phen is instrumental in facilitating energy transfer from host to emitter. Finally, highly efficient red EL devices with the highest current efficiency, power efficiency and brightness up to 58.98 cd A(-1) (external quantum efficiency (EQE) of 21%), 61.73 lm W(-1) and 100870 cd m(-2), respectively, were obtained by appropriately decreasing the doping concentration of iridium complex. At certain brightness of 1000 cd m(-2), EL current efficiency up to 51.94 cd A(-1) (EQE = 18.5%) was retained. Our investigation extends the application of rare earth complexes in EL devices and provides a chance to improve the device performances.

13.
J Virol ; 89(18): 9200-12, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26109732

RESUMO

UNLABELLED: Interferon alpha (IFN-α) is an approved medication for chronic hepatitis B therapy. Besides acting as an immunomodulator, IFN-α elicits a pleiotropic antiviral state in hepatitis B virus (HBV)-infected hepatocytes, but whether or not IFN-α impedes the late steps of the HBV life cycle, such as HBV secretion, remains elusive. Here we report that IFN-α treatment of HepAD38 cells with established HBV replication selectively reduced HBV virion release without altering intracellular viral replication or the secretion of HBV subviral particles and nonenveloped capsids. In search of the interferon-stimulated gene(s) that is responsible for the reduction of HBV virion release, we found that tetherin, a broad-spectrum antiviral transmembrane protein that inhibits the egress of a variety of enveloped viruses, was highly induced by IFN-α in HepAD38 cells and in primary human hepatocytes. We further demonstrated that the expression of full-length tetherin, but not the C-terminal glycosylphosphatidylinositol (GPI) anchor-truncated form, inhibited HBV virion egress from HepAD38 cells. In addition, GPI anchor-truncated tetherin exhibited a dominant-negative effect and was incorporated into the liberated virions. We also found colocalization of tetherin and HBV L protein at the intracellular multivesicular body, where the budding of HBV virions takes place. In line with this, electron microscopy demonstrated that HBV virions were tethered in the lumen of the cisterna membrane under tetherin expression. Finally, knockdown of tetherin or overexpression of dominant negative tetherin attenuated the IFN-α-mediated reduction of HBV virion release. Taken together, our study suggests that IFN-α inhibits HBV virion egress from hepatocytes through the induction of tetherin. IMPORTANCE: Tetherin is a host restriction factor that blocks the egress of a variety of enveloped viruses through tethering the budding virions on the cell surface with its membrane anchor domains. Here we report that interferon directly and selectively inhibits the secretion of HBV virions, but not subviral particles or nonenveloped capsids, through the induction of tetherin in hepatocyte-derived cells. The antiviral function of tetherin requires the carboxyl-terminal GPI anchor, while the GPI anchor deletion mutant exhibits dominant negative activity and attaches to liberated HBV virions. Consistent with the fact that HBV is an intracellular budding virus, microscopy analyses demonstrated that the tethering of HBV virions occurs in the intracellular cisterna and that tetherin colocalizes with HBV virions on the multivesicular body, which is the HBV virion budding site. Our study not only expands the antiviral spectrum of tetherin but also sheds light on the mechanisms of interferon-elicited anti-HBV responses.


Assuntos
Antígenos CD/biossíntese , Antivirais/farmacologia , Capsídeo/metabolismo , Vírus da Hepatite B/fisiologia , Liberação de Vírus/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos , Antígenos CD/genética , Capsídeo/ultraestrutura , Linhagem Celular , Proteínas Ligadas por GPI/biossíntese , Proteínas Ligadas por GPI/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Glicosilfosfatidilinositóis , Vírus da Hepatite B/ultraestrutura , Hepatócitos/metabolismo , Hepatócitos/ultraestrutura , Hepatócitos/virologia , Humanos , Interferon-alfa/farmacologia
15.
Antimicrob Agents Chemother ; 59(1): 206-16, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25348530

RESUMO

Endoplasmic reticulum (ER)-resident glucosidases I and II sequentially trim the three terminal glucose moieties on the N-linked glycans attached to nascent glycoproteins. These reactions are the first steps of N-linked glycan processing and are essential for proper folding and function of many glycoproteins. Because most of the viral envelope glycoproteins contain N-linked glycans, inhibition of ER glucosidases with derivatives of 1-deoxynojirimycin, i.e., iminosugars, efficiently disrupts the morphogenesis of a broad spectrum of enveloped viruses. However, like viral envelope proteins, the cellular receptors of many viruses are also glycoproteins. It is therefore possible that inhibition of ER glucosidases not only compromises virion production but also disrupts expression and function of viral receptors and thus inhibits virus entry into host cells. Indeed, we demonstrate here that iminosugar treatment altered the N-linked glycan structure of angiotensin I-converting enzyme 2 (ACE2), which did not affect its expression on the cell surface or its binding of the severe acute respiratory syndrome coronavirus (SARS-CoV) spike glycoprotein. However, alteration of N-linked glycans of ACE2 impaired its ability to support the transduction of SARS-CoV and human coronavirus NL63 (HCoV-NL63) spike glycoprotein-pseudotyped lentiviral particles by disruption of the viral envelope protein-triggered membrane fusion. Hence, in addition to reducing the production of infectious virions, inhibition of ER glucosidases also impairs the entry of selected viruses via a post-receptor-binding mechanism.


Assuntos
Antivirais/farmacologia , Coronavirus Humano NL63/patogenicidade , Glucosidases/antagonistas & inibidores , Peptidil Dipeptidase A/metabolismo , Vírus da SARS/patogenicidade , Internalização do Vírus/efeitos dos fármacos , Antivirais/química , Coronavirus Humano NL63/efeitos dos fármacos , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacologia , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Humanos , Imino Açúcares/química , Imino Açúcares/farmacologia , Terapia de Alvo Molecular , Peptidil Dipeptidase A/química , Vírus da SARS/efeitos dos fármacos , Glicoproteína da Espícula de Coronavírus/metabolismo
16.
Antimicrob Agents Chemother ; 59(2): 1273-81, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25512416

RESUMO

Chronicity of hepatitis B virus (HBV) infection is due to the failure of a host to mount a sufficient immune response to clear the virus. The aim of this study was to identify small-molecular agonists of the pattern recognition receptor (PRR)-mediated innate immune response to control HBV infection. To achieve this goal, a coupled mouse macrophage and hepatocyte culture system mimicking the intrahepatic environment was established and used to screen small-molecular compounds that activate macrophages to produce cytokines, which in turn suppress HBV replication in a hepatocyte-derived stable cell line supporting HBV replication in a tetracycline-inducible manner. An agonist of the mouse stimulator of interferon (IFN) genes (STING), 5,6-dimethylxanthenone-4-acetic acid (DMXAA), was found to induce a robust cytokine response in macrophages that efficiently suppressed HBV replication in mouse hepatocytes by reducing the amount of cytoplasmic viral nucleocapsids. Profiling of cytokines induced by DMXAA and agonists of representative Toll-like receptors (TLRs) in mouse macrophages revealed that, unlike TLR agonists that induced a predominant inflammatory cytokine/chemokine response, the STING agonist induced a cytokine response dominated by type I IFNs. Moreover, as demonstrated in an HBV hydrodynamic mouse model, intraperitoneal administration of DMXAA significantly induced the expression of IFN-stimulated genes and reduced HBV DNA replication intermediates in the livers of mice. This study thus proves the concept that activation of the STING pathway induces an antiviral cytokine response against HBV and that the development of small-molecular human STING agonists as immunotherapeutic agents for treatment of chronic hepatitis B is warranted.


Assuntos
Antivirais/farmacologia , Animais , Antivirais/uso terapêutico , Linhagem Celular , Vírus da Hepatite B/efeitos dos fármacos , Vírus da Hepatite B/fisiologia , Hepatite B Crônica/tratamento farmacológico , Imunidade Inata/efeitos dos fármacos , Proteínas de Membrana/agonistas , Camundongos , Replicação Viral/efeitos dos fármacos , Xantonas/uso terapêutico
17.
Nanoscale Res Lett ; 9(1): 372, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25114660

RESUMO

The single scratching test of polymer polycarbonate (PC) sample surface using an atomic force microscope (AFM) diamond tip for fabricating ripple patterns has been studied with the focus on the evaluation of the effect of the tip scratching angle on the pattern formation. The experimental results indicated that the different oriented ripples can be easily machined by controlling the scratching angles of the AFM. And, the effects of the normal load and the feed on the ripples formation and their periods were also studied. Based on the ripple pattern formation, we firstly proposed a two-step scratching method to fabricate controllable and oriented complex three-dimensional (3D) nanodot arrays. These typical ripple formations can be described via a stick-slip and crack formation process.

18.
Nanoscale Res Lett ; 9(1): 212, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24940171

RESUMO

This letter presents a novel atomic force microscopy (AFM)-based nanomanufacturing method combining the tip scanning with the high-precision stage movement to fabricate nanochannels with ladder nanostructure at the bottom by continuous scanning with a fixed scan size. Different structures can be obtained according to the matching relation of the tip feeding velocity and the precision stage moving velocity. This relationship was first studied in detail to achieve nanochannels with different ladder nanostructures at the bottom. Machining experiments were then performed to fabricate nanochannels on an aluminum alloy surface to demonstrate the capability of this AFM-based fabrication method presented in this study. Results show that the feed value and the tip orientation in the removing action play important roles in this method which has a significant effect on the machined surfaces. Finally, the capacity of this method to fabricate a large-scale nanochannel was also demonstrated. This method has the potential to advance the existing AFM tip-based nanomanufacturing technique of the formation these complex structures by increasing the removal speed, simplifying the processing procedure and achieving the large-scale nanofabrication.

19.
Antiviral Res ; 107: 56-65, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24792753

RESUMO

Virus infection of host cells is sensed by innate pattern recognition receptors (PRRs) and induces production of type I interferons (IFNs) and other inflammatory cytokines. These cytokines orchestrate the elimination of the viruses but are occasionally detrimental to the hosts. The outcomes and pathogenesis of viral infection are largely determined by the specific interaction between the viruses and their host cells. Therefore, compounds that either inhibit viral infection or modulate virus-induced cytokine response should be considered as candidates for managing virus infection. The aim of the study was to identify compounds in both categories, using a single cell-based assay. Our screening platform is a HEK293 cell-based reporter assay where the expression of a firefly luciferase is under the control of a human IFN-ß promoter. We have demonstrated that infection of the reporter cell line with a panel of RNA viruses activated the reporter gene expression that correlates quantitatively with the levels of virus replication and progeny virus production, and could be inhibited in a dose-dependent manner by known antiviral compound or inhibitors of PRR signal transduction pathways. Using Dengue virus as an example, a pilot screening of a small molecule library consisting of 26,900 compounds proved the concept that the IFN-ß promoter reporter assay can serve as a convenient high throughput screening platform for simultaneous discovery of antiviral and innate immune response modulating compounds. A representative antiviral compound from the pilot screening, 1-(6-ethoxybenzo[d]thiazol-2-yl)-3-(3-methoxyphenyl) urea, was demonstrated to specifically inhibit several viruses belonging to the family of flaviviridae.


Assuntos
Antivirais/isolamento & purificação , Fusão Gênica Artificial , Avaliação Pré-Clínica de Medicamentos/métodos , Genes Reporter , Fatores Imunológicos/isolamento & purificação , Interferon beta/biossíntese , Vírus de RNA/efeitos dos fármacos , Linhagem Celular , Ensaios de Triagem em Larga Escala , Humanos , Interferon beta/genética , Luciferases de Vaga-Lume/análise , Luciferases de Vaga-Lume/genética , Regiões Promotoras Genéticas
20.
Proc Natl Acad Sci U S A ; 111(18): 6756-61, 2014 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-24753610

RESUMO

IFNs are a family of cytokines that are essential for the antiviral response in vertebrates. Not surprisingly, viruses have adapted to encode virulence factors to cope with the IFN response. Intriguingly, we show here that all three types of interferons, IFN-α, IFN-γ, and IFN-λ, efficiently promote infection by a human coronavirus, HCoV-OC43, one of the major etiological agents of common cold, through the induction of IFN-inducible transmembrane (IFITM) proteins. IFITMs typically exert their antiviral function by inhibiting the entry of a broad spectrum of viruses into their host cells, presumably by trapping and degrading invading virions within the endocytic compartments. In contrast, HCoV-OC43 uses IFN-induced human IFITM2 or IFITM3 as an entry factor to facilitate its infection of host cells. Reverse genetics analyses suggest that the structural motifs critical for the IFITM proteins' enhancement of HCoV-OC43 infection are distinct from those required for inhibiting infection by other viruses. We also present evidence showing that IFITM family members work as homo- and hetero-oligomers to modulate virus entry. The observed enhancement of HCoV-OC43 infection by IFNs may underlie the propensity of the virus to invade the lower respiratory tract under inflammatory conditions.


Assuntos
Coronavirus Humano OC43/patogenicidade , Interferons/metabolismo , Proteínas de Membrana/biossíntese , Sequência de Aminoácidos , Animais , Linhagem Celular , Infecções por Coronavirus/etiologia , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/virologia , Coronavirus Humano OC43/imunologia , Coronavirus Humano OC43/fisiologia , Citocinas/metabolismo , Interações Hospedeiro-Patógeno , Humanos , Proteínas de Membrana/química , Proteínas de Membrana/genética , Camundongos , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Virulência/imunologia , Internalização do Vírus
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